Gene Therapy Today

Clinical Trials for Gene Therapy

Before a gene therapy is approved for use, it must go through extensive testing in the laboratory and in people. Here are the steps a gene therapy must pass on its way to becoming a viable treatment.

How is gene therapy studied?

Clinical trials

Like with any drug therapy, gene therapy starts as an idea or discovery in a lab. And before it can be prescribed or administered, it must be proven safe and effective through Clinical trialsa study that measures the safety and effectiveness of a medication

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. These trials are highly regulated by the US Food and Drug Administration (FDA)an agency in the US federal government whose mission is to protect public health by making sure that drugs, medical devices, and other equipment are safe and effective

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and controlled by the companies or research institutes that are developing gene therapies.1 Any person participating in these trials must be informed verbally and in writing about the potential risks and benefits of participating in the trial.2,3 

Before a gene therapy is tested in clinical trials, researchers must study it first in a laboratory. These studies are called Preclinical Studya required study that measures the safety of a medication in animals before it is allowed to be tested in people

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, and help researchers decide what gene therapies are ready to put into clinical trials. When a gene therapy is ready for a clinical trial in people living with a specific disease, the manufacturer submits an application to the US Food and Drug Administration (FDA) to launch a clinical trial.4 There are usually 3 phases to each clinical trial, each involving a slightly greater number of people.5,6

  • A Phase 1 clinical study is conducted in a small group of people to test the drug for safety and determine its appropriate dose, dosing schedule, and method of administration (people without disease are usually the participants in Phase 1 studies of traditional drugs)

  • A Phase 2 clinical study is conducted in a group of people with a disease or condition to test the drug’s efficacy (how well it works) and safety

  • A Phase 3 clinical study is conducted in a larger group of people with a disease or condition

*Phase 1 and 2 are usually combined in gene therapy studies. Most gene therapies are not tested in healthy volunteers because of the possible risk of permanent effects and invasive administration.6

Image of gene therapy patients in clinical trials

*Phase 1 and 2 are usually combined in gene therapy studies. Most gene therapies are not tested in healthy volunteers because of the possible risk of permanent effects and invasive administration.6

How long does it take to get a gene therapy approved?

It can take many years (even decades) for a gene therapy to move from discovery, through preclinical and clinical trials, and into approval. Variables that affect the time it takes to get a gene therapy approved include: study planning, patient enrollment, time to approve trial, ethics reviews, and funding.

How are gene therapy clinical trials unique?

Though the specifics will be different for each gene therapy moving into clinical trials, some of the key differences between trials of gene therapies and trials of traditional pharmaceutical products are:

  • The nature of the risks of gene therapy products can be different from those typically associated with traditional pharmaceuticals6
    • A gene therapy alters the cells of a person to target a genetic change. The targeted genetic change is expected, but it is difficult to know how this change will affect the body long-term without more data
  • Early-phase clinical trials of gene therapy products often involve preclinical challenges, chemistry, manufacturing, control (CMC) processes, and clinical safety questions that are less common in the development of traditional pharmaceuticals6
  • Questions about durability of response for gene therapy products often can’t be fully answered in pre-market trials of reasonable size and duration; approved gene therapies use long-term follow-up studies and registries to capture and collect additional years of safety and Efficacythe ability for a medication to achieve its desired effect

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     data
  • There are smaller trial populations because only people with the disease (or change/mutation) are enrolling and recent studies have focused on genetic diseases and certain types of cancer4,6,8
  • There is an extensive long-term follow-up period to determine the duration of effect and an ongoing safety profile9
Image of laboratory for conducting gene therapy clinical trials

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References

1. Food and Drug Administration. Human gene therapy for rare diseases: guidance for industry. January 2020. Accessed March 4, 2020. https://www.fda.gov/media/113807/download 2. Food and Drug Administration. Informed consent for clinical trials. Accessed March 4, 2020. https://www.fda.gov/patients/clinical-trials-what-patients-need-know/informed-consent-clinical-trials 3. National Institutes of Health. ClinicalTrials.gov. Learn about clinical trials. Accessed March 16, 2020. https://www.clinicaltrials.gov/ct2/about-studies/learn 4. Food and Drug Administration. Guidance for industry: preclinical assessment of investigational cellular and gene therapy products. Accessed March 4, 2020. https://www.fda.gov/media/87564/download 5. Food and Drug Administration. Step 3: clinical research. Accessed March 4, 2020.  https://www.fda.gov/patients/drug-development-process/step-3-clinical-research 6. Food and Drug Administration. Considerations for the design of early-phase clinical trials of cellular and gene therapy products: guidance for industry. Accessed March 4, 2020. https://www.fda.gov/media/106369/download 7. Food and Drug Administration. FDA continues strong support of innovation in development of gene therapy products. Press release. Accessed March 4, 2020. https://www.fda.gov/news-events/press-announcements/fda-continues-strong-support-innovation-development-gene-therapy-products 8. American Society of Gene and Cell Therapy. Trials finder. Accessed March 16, 2020. https://app.emergingmed.com/asgct/home 9. Food and Drug Administration. Long term follow-up after administration of human gene therapy products: guidance for industry. Accessed March 4, 2020. https://www.fda.gov/media/113768/download

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